Removes optional platform, which only existed for tests.
There is now a global `@import("testing.zig").test_app` available. This is setup
when the test runner starts, and cleaned up at the end of tests. Individual
tests don't have to worry about creating app, which I assume was the reason I
Platform optional, since that woul dhave been something else that needed to be
setup.
Outputs in logfmt in release and a "pretty" print in debug mode. The format
along with the log level will become arguments to the binary at some point in
the future.
Replaces the existing, very specialized Notification with something more
general.
Currently, the existing page_navigate and page_navigated have been migrated.
Telemetry's page navigation event now also hooks into these events to generate
the telemetry record.
